Well, if one insists on an animal, IMO, there's only one animal that fits the bill: the platypus.
It looks like it's thrown together from pieces of other animals (like Perl from pieces of other languages), it's ugly for people not familiar with it, but adorable for people who love it. And it has unique features, not found in other mammals, like laying eggs, and being poisonous - just like Perl has unique features.
in reply to New mascot for Perl
But no doubt that O'Reilly is already using the platypus for some book or another.